DESCRIPTION: For replication of influenza virus, 3 viral polymerase (3P) proteins (PA, PB1 and PB2) are necessary. The long term goal of this proposal is to find ways to interfere with the polymerase activity for a safe live virus vaccine. The aims of this proposal are: 1. how the polymerase complex is formed, 2. what are the functions of each polymerase protein, 3. what are the domains and sequence requirements for these functions, 4. what are the functions of nucleocapsid protein (NP) in modulating the polymerase activity, and 5. what are the requirements of type (A, B, and C) specificity for viral polymerases?